1. Field of the Invention apparatus using a photosensitive and pressure sensitive sheet.
The present invention also relates to a media cartridge, which contains such a photosensitive and pressure sensitive sheet, for use in such an image forming apparatus.
2. Description of the Related Art
As one of various kinds of image forming apparatuses, there is an image forming apparatus using a photosensitive and pressure sensitive sheet.
Such a sensitive sheet is made of a resin film coated with microcapsules. The microcapsules contain photohardening resin and coloring material in its shell. The photohardening resin is polymerized by light. This sensitive sheet makes a pair with an image receiver sheet, for performing its color development.
That is to say, the receiver sheet is coated with developing material which develops the coloring material in the microcapsules when the microcapsules are ruptured and the coloring material is flown out therefrom.
The microcapsules are hardened by the polymerization of the resin caused by the illumination of the exposure light for forming a latent image such as a light reflected from the original onto the sensitive sheet. Thus, a latent image is formed on the sensitive sheet. Then, by superposing the receiver sheet onto the sensitive sheet and applying a pressure force thereon, the microcapsules which are not hardened are ruptured, thus an image is formed on the receiver sheet by the development of the coloring material of the ruptured microcapsules in cooperation with the developing material of the receiver sheet.
In the image forming apparatus using such a photosensitive and pressure sensitive sheet, the unused sensitive sheet should be guarded from light and pressure so a to maintain its photosensitive property and pressure sensitive property.
Accordingly, a media cartridge is used in this kind of image forming apparatus for accommodating the unused sensitive sheet in a rolled form so as to guard the sensitive sheet from external light and pressure. The media cartridge is provided with a supplying shaft on which the unused sensitive sheet is rolled to supply the sensitive sheet therefrom. The media cartridge is also provided with a winding-up shaft to wind up the used sensitive sheet. The media cartridge is detachably mounted to a main body of the image forming apparatus so as to allow an exchange of the sensitive sheet by exchanging the media cartridge.
When the media cartridge is mounted to the main body, the tip portion of the sensitive sheet, which is pulled out from the supplying shaft of the media cartridge, is set through various kinds of rollers and a specific transport path, which are provided in the exposure section and the pressure developing section in the main body of the image forming apparatus, to the winding-up shaft of the media cartridge. Then, the image forming operation can be performed as the unused sensitive sheet is drawn out from the media cartridge and transported through the exposure section and the pressure developing section of the main body, and then the used sensitive sheet is returned to the media cartridge.
However, in this kind of image forming apparatus, once the media cartridge is set to the main body, it is difficult to exchange the sensitive sheet in its half used condition in the media cartridge. Particularly, it is necessary to cut once the sensitive sheet in order to remove the media cartridge out of the main body, since the sensitive sheet is wound between the supplying shaft and the winding-up shaft through the exposure section and the developing section provided in the main body. Further, if the sensitive sheet, which is in a half used condition, is to be set again to the main body, the tip portion of the sensitive sheet must be set again appropriately through the exposure section and the developing section in the main body, resulting in that a length of the sensitive sheet needed for such an initial setting process is wasted. In addition, such an initial setting process is troublesome and time consuming since it should be performed in a relatively narrow space in the main body.
The pressure force needed for the pressure developing process at the developing section is relatively large, so it is also difficult to achieve a condition to apply such a pressure force and a condition to release the applied pressure force.